A biaxially-stretch-blow-molded container made of polyethylene terephthalate (PET) resin or of polypropylene (PP) resin exhibits numerous excellent properties, and is thus used in various fields.
In general, such container is molded from an injection-molded preform in a bottomed cylindrical shape, which is stretched and deformed into an expanded shape as being heated to a temperature at which a stretching effect is observed.
In other words, as shown in FIG. 16 (corresponding to FIG. 12 of PTL 1), a preform 31 heated to a temperature which renders a stretching effect is installed into a blow mold 101 in a state where the mouth tube portion 32 is protruding above and a neck ring 33, which is integrally formed circumferentially on the lower edge of the outer circumferential surface of the mouth tube portion 32 of the preform 31, is engaged with a neck supporting flange portion 103. Further, with a guide tube portion 110 as the tip of the blow nozzle 104 being loosely fitted into the mouth tube portion 32 of the preform 31, the preform 31 is stretched in the axial direction by means of a stretching rod 108 inserted through an insertion hole 111 formed by penetrating the central portion of a blow nozzle 104 while being simultaneously stretched in a radial direction by means of a blow air serving as a pressurized fluid blown through the insertion hole 111, to thereby mold a container (bottle body) 41.
Further, PTL 2 discloses an invention relating to a method for blow molding a preform using a liquid, instead of a blow air, as a pressurized fluid.
In such molding methods, a content liquid, such as beverages, cosmetics, detergents, drugs, and the like, which are to be filled into a final product may be used as the liquid, so as to eliminate the filling process, to thereby simplify the production line.